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Light-Based Memory Chip Is First To Permanently Store Data
sciencehabit writes: Scientists have developed the first ever memory chip that’s entirely light-based and can store data permanently. Sciencemag reports: "Today's electronic computer chips work at blazing speeds. But an alternate version that stores, manipulates, and moves data with photons of light instead of electrons would make today's chips look like proverbial horses and buggies. Now, one team of researchers reports that it has created the first permanent optical memory on a chip, a critical step in that direction. If a more advanced photonic memory can be integrated with photonic logic and interconnections, the resulting chips have the potential to run at 50 to 100 times the speed of today's computer processors."
Yes. I am having a hard time finding a good article on this, so I will attempt to explain. I'm a software guy with limited VLSI and electrical experience, so I bet 100 people will jump in and correct me on parts of this. But here goes...
I think the hope is that optical circuits would be lower resistance, be less susceptible to heat, not cause magnetic fields, and not act as transmitters or receivers.
When electricity passes through a wire, it experiences resistance. That resistance slows the signal and creates waste heat. "Slows the signal" means two things. One is that it takes longer for the current to flow to the destination. Two is that since current was lost to heat, it takes longer for the destination to sink enough current to turn on. As the wire heats, it also becomes a poorer conductor too.
Also, due to the way transistors work, they briefly short-circuit while they are switching. So the longer it takes for the current to build up at the gate's transistor, the longer it short circuits. Which produces heat too.
Another problem is that electricity in a wire creates a magnetic field. This creates more losses, but also can cause some of the electricity to jump to a neighboring wire. As transistors and wires get smaller, it becomes increasingly likely that signals will "short circuit" and jump to a neighboring wire.
Electronic circuits are also sources of, and susceptible to, external noise. A 2GHz CPU is a (weak) 2Ghz transmitter. And a 2Ghz transmitter could induce a voltage on wires within the CPU. I don't know how much of a problem this is though, since the wires in the CPU are very small.